Adjustable sparking plug



May 21, 1929. HQLRQYQ 1,714,463

ADJUSTABLE SPARKING PLUG Filed Aug. 2?, 1928 a??? //r/m GEORGE HOLROYD,

Patented May 21, 1929.

UNITED STATES,

' GEORGE HOLROYD, or

HALIFAX, ENGLAND.

i ADJUSTABLE SPARKING PLUG.

Application filed August 27, 1928, Serial No,

This invent ion relates to adjustable sparking plugs for use in internal combustion engines. By the term adjustable sparking plugs is meant sparking plugs in. which the gap or gaps which the spark is impelled to jump may be adjusted in length by moving one of the electrodes towards or away from the other or others.

One object of the invention is to provide an adjustablesparking plug which shall be simple and cheap to construct. This object is attained by'providing a single member which serves both to clamp or compress the insulation of the plug and also to position the adjustable electrode.

Another object of the invention is to provide an adjustable sparking plug which shall remain substantially gas tight even while it is being adjusted, and this object is attained by providing a metal tube into and through which the adjustable electrode is closely fitted and which is not itself moved by the act of adjusting.

Other objects and advantages will hereinafter appear.

The invention will be mor'e particularly described and ascertained in connection with the accompanying drawings, in which Figure 1 showsin half sectional elevation one construction of sparking plug in accordance with this invention; Figure 2 shows in plan view the sparking plug shown in Figure 1; Figure 3 shows in elevation a plurality of sparking plugs as shown in Figures 1 andQ, arranged for simultaneous adjustment by Bowden or similar cable control from the cockpit of an aeroplane, for example,Figure lis a planv view of Figure 3.

Referring to the drawings, the sparking plug shown in Figures 1 and 2 comprises a metal tube 1, about which is a tight longitudinal wrapping 2 of-sheet mica or other appropriate insulating material. This wrapping is surrounded by a plurality of trans verse annular mica or other washers 3 which are compressed between a metal gland 4 and a bridge piece 5 which latter is screwed down on to a thread cut in the upper exterior of the tube and thus serves to clamp and com press longitudinally the insulating material. The metal gland at is firmly compressed around the rolled sheet mica2 in accordance with usual well known practice. The plug comprises two electrodes 6 and 7, the former being fixed and being attached to or formed 302,219, and in Great Britain May 12, 1927 integral with the main body 8 which is adapted to be screwed into anengine cylinder,

while the latter electrode 7 is'constituted by a rod which is slidablc in the tube. 1 and makes a substantial gas tight lit therein. The

'gl'and' l is held in .position by means of the usual hexagon headed screwed sleeve 9, which compresses a copper-asbestos washer between the said gland and the inner base of the main body 8. The electrode 7 passes up from the tube 1 and is screwedat 10 into andthrough a hole in'the upper part 11 of the said bridge screwing the electrode to a desired extent.

Preferably the screw threadupon the electrode? is such that one complete turn there of back from the fully screwed down position gives a standard spark gap. d

On the upper end of the electrode 7 is a milled nut 12 which "is locked thereon by means of a set screw 13, the upper end of the said nut being squared and passing into a similarly squared hole in an insulating cover 1 1-, so that if the cover 14: is turned, the electrode 7 is turned also. The cover is held in position and electrical connection is made to the electrode 7 by means of member 15 'f screwed on to the upper end of the said elecr trode,the said member 15 bemg formed, for

examplejinto a ball 16 so as to be engageableby means of any known springconnector (not shown). on the end of the ignition lead. 17' i'sa' spring finger carri'ed'at its lower end .on the bridge piece, 5, and pressing into the millings' on the nut 12, so that the said nut is maintained against the effects ofvibration in whatever position it may be set. The end of the tube 1 and insulation thereabout is preferably chamfered, as shown.

In order to' ensure that the plug is absolutely gas tight and will remain so, a packing gland 18 is screwed on to the upper end of the tube 1 and surrounds the electrode 7.

It will be seen that with the construction shown, the spark gap is readilyadjustable, While the points can readily be cleaned by screwing the electrodes together and then separating them. Further, the gap can be adjusted while the engine is running, since the cover 14 is insulated.

Figures 3 and 4 show a plurality of sparking plugs SP SP SP and SP as shown in Figures 1 and 2, arranged for common remote adjustment, for example, from the cockpit of an aeroplane to whose engine said plugs are fitted. Surrounding the insulating cover l l of each plug is a clamping device comprising two portions 19, 20, which are clamped together and around said cover by means of bolts and nuts 21, as shown. The portions 19, 20 co-operate to form an arm 22, as shown, which extends radially outwards and is provided with a screwed hole 28. Short rods 24 are screwed into the holes 23 of the arms of the plugs, andnuts 25 are provided whereby the rods 24 may be locked in any'position. The ends of the rods 24 are formed with holes 26 into which may be passed wires or thin rods. Clamped about the main body of the plug SP is a second clamping device comprising two portions 27, 28 clamped together and about said body by means of bolts and nuts 29. The portion 28 terminates in a rearward and upwardly eX- tending arm 30 which carries, at its upper end, a screwed sleeve 31 and locknut 32 of usual pattern for receiving the end of a Bowden casing 33. The Bowden wire passes through the sleeve 31 and is attached to the rod 24 of the arm 22 of the plug SP The arms 22 ofplugs SP SP SP and SP? are coupled together by wires 34, so as to be operable in common from a lever 35 ofknown arrangement, situated, for example, in the cockpit of an aeroplane, the lever being shown in mid position. 36 is a return spring, one end of which passes through the hole in the rod 24 of the arm 22 of the plug SP and the other end ofwhich is fixed to some relative fixed point (not shown).

Obviouslythe arrangement may readily be adapted to any number of sparking plugs, while any convenient form of operation other than Bowden wire may be employed.

In the claims which follow, the term spark receiving means is employed broadly to refer to the electrode or electrodes, of which there may be any number per plug, which are in the return ignition circuit.

WVhat I claim'is 1. An adjustable sparking plug comprising a main body, a tube therein, compressible insulating means about said tube, means for holding said insulating means in said body,an electrode slidably mounted in said tube and substantially gas tight in all positions therein, a parallel-sided carrier adjustably connected to the upper end of the electrode, a yieldable means connecting the carrier and the bridge for retaining thecarrier and electrode in an adjusted position, and a single bridge piece screwed upon said tube and screwing down upon and compressing said insulating means, said bridge piece having a tapped hole into and through which said electrode is screwable.

2. An adjustable sparking plug compris ing a main body, a tube, insulating means about said tube, said tube and the insulation thereabout being chamfered at the lower end, means for holding said insulating means in said body, an electrode slidably mounted in said tube and substantially gas tight therein in all positions, and a single means carried by said tube for clamping and compressing said insulating means and retaining said electrode in any position to which it has been adjusted.

3. A plurality of sparking plugs each having a longitudinally adjustable electrode including a rotatable element, and remote control means for simultaneously adjusting said electrode comprising a holderfixed to one plug for supporting said remote control means, clamps supported on the respective rotatable elements, and means connect-ed to said clamps for simultaneously actuating said electrodes by said remote control means.

In testimony that I claim the foregoing as my invention, 1 have signed my name this 16th day of August, 1928.

(inonen HOLROYD. 

